Knight Frank said 23,000 buildings could be suitable for rooftop development in Zones 1 and 2, and the volume of the unused plots across the same area is equivalent to eight Burj Khalifa towers, "crucially without the corresponding impact on London’s skyline".

In order to carry out the research, Knight Frank developed a method to "systematically analyse the potential of each building", called Skyward.

"Skyward is a fantastically powerful tool for identifying development opportunities to unlock thousands of new homes in London and ease housing supply pressures, particularly in those areas where availability of land is becoming increasingly rare. It also has the potential to add an objective approach to planning decisions on a semi-permissive basis," said residential development partner Charles Dugdale.